To eliminate unnecessary wastage during the cutting process of any type of material such as wood, textiles etc, it is important to have adequate control in the alignment mechanism. Laser beams are widely used for alignment purposes. In making a laser beam draw a line of light on an object, it has been common to employ a polygonalprismatic mirror rotated at a high speed, to which a laser beam is incident to make the reflected laser beam sweep the surface of the object. However, this arrangement calls for a complicated device which rotates the mirror at a high speed.
Another tool which has recently arrived on the market and has proven to be relatively successful in the mechanics of alignment is a He-Ne laser with a lens attachment (e.g. cylindrical lens) on the front for expanding the beam in one direction. Ideally the projected laser beam should be a well-defined line being uniform in both width and intensity along its length. However, the design of these elements has been based on a somewhat trial and error approach resulting in a laser line which varies significantly in intensity along its length.
U.S. Pat. No. 4,589,738 May 20, 1986 (Ozaki) describes various other optical arrangements for projecting a laser beam in a linear pattern, e.g. line, square etc. The patent uses a convex reflector or a concave lens to spread a laser beam radially and then a cylindrical-concave reflector to converge the beam linearly to project a line etc. Although the arrangements mentioned in the patent are complex requiring a variety of optical elements in strict alignment, each of the systems suffers from the same drawback as found with the cylindrical lens i.e. non-uniformity in intensity along the length of the line. The distribution is in fact what is known gaussian which is the same as that found across the beam leaving the laser head.
The present invention solves these prior art problems associated with the line projection of a laser beam. A new optical lens element of the present invention expands a laser beam in one direction to project a beam line of uniform intensity and width having well defined ends.